This invention relates to a method of loading a pack of clutch plates into an outer clutch element of a clutch for a motor vehicle automatic transmission.
A typical motor vehicle automatic transmission includes a plurality of clutches between planetary gear sets of the transmission which are turned on and off to vary the reduction ratio of the transmission. Each clutch commonly includes an outer clutch element often identified as a housing or xe2x80x9cdrumxe2x80x9d, an inner clutch element, a clutch pack, and a piston in the drum. The clutch pack includes a plurality of flat reaction plates rotatable with the drum and a plurality of friction plates stacked between the reaction plates and rotatable with the inner clutch element. When the clutch is off, the piston is retracted and the reaction plates and the drum are freely rotatable relative to the friction plates and the inner clutch element. When the clutch is on, the piston is thrust by hydraulic pressure against the clutch pack to squeeze together the reaction plates and the friction plates and thereby frictionally couple together the drum and the inner clutch element for unitary rotation. Commonly, the reaction plates have outside spline teeth which cooperate with spline grooves in a cylindrical wall of the drum in coupling the reaction plates to the drum for unitary rotation. Typically, the clutch pack is manually loaded into the drum by a person who drops the clutch pack vertically into the drum after rotating the reaction plates to align their outside spline teeth with the spline grooves in the drum. Manual loading of the clutch pack is especially the norm or the only method when clearances are inadequate for use of mechanical devices. Because the person manually loading the clutch pack can work comfortably with only a fraction of the reaction and friction plates constituting the complete clutch pack, the task of manually loading the complete clutch pack is slow and relatively uneconomical. Accordingly, manufacturers continue to seek improved methods of loading a clutch pack into an outer clutch element.
This invention is a new and improved method of loading a clutch pack into a drum or outer clutch element of a clutch for a motor vehicle automatic transmission. The clutch pack includes a plurality of friction plates between a plurality of reaction plates. Each reaction plate has a plurality of outside spline teeth slidably received in a corresponding plurality of straight spline grooves in a cylindrical wall of the drum. The method according to this invention of loading the clutch pack into the drum includes the steps of forming a seat on an outboard end of the cylindrical wall of the drum interrupted by a plurality of notches where the spline grooves intersect the seat, supporting the drum on a platform with the outboard end of the drum opening upward, supporting the clutch pack in a sleeve above the seat on the drum, releasing the clutch pack for vertical descent in the sleeve until the outside spline teeth on the bottom one of the reaction plates bear on the seat on the drum, and vibrating the drum perpendicular to the reaction plates at high frequency and low amplitude to induce rotation of the clutch pack on the seat within the sleeve. As the clutch pack rotates, the outside spline teeth on the bottom one of the reaction plates traverse the seat until attaining registry with the notches therein. Then, the reaction plates and the smaller friction plates therebetween descend in succession by gravity into the drum until the sleeve is empty and the drum is loaded. The seat on drum may be an inside chamfer or an annular flat wall on the cylindrical wall of the drum. The method according to this invention of loading a clutch pack into a drum proceeds more rapidly and efficiently than the prior manual method and is more ergonomically correct than the prior manual method.